(1) Field of the Invention
This invention relates to bowling and more particularly to an improved bowling lane. More particularly still, this invention relates to a so-called oiless or oil-free bowling lane surface.
(2) Description of the Prior Art
As is well known to designers, builders and operators of bowling centers, as well as to the average bowling devotee, bowling lanes are subject to severe stresses and wear due to the weight of the bowling balls and the fact that such balls may not be deposited or rolled smoothly upon the surface of the lane, but may instead be lofted or lifted and then dropped upon the lane surface at the end of the bowler3 s delivery. Even where the ball is smoothly rolled down the lane without any significant lofting, the lane is subject to considerable force and wear during the rolling of a heavy bowling ball over the surface. Since bowling balls weigh several pounds and inherently roll or slide over the surface of the lane with only minimum surface-to-surface contact with the lane surface due to the spherical configuration of the ball, the physical forces developed directly under the bowling ball become quite severe due to the concentration of weight and any frictional components present at the small contact surface, which minimum contact surface is necessary to enable the ball to progress evenly and efficiently down the lane. During delivery, furthermore, the ball tends to be rotated backwards due to the swing of the bowlers arm during delivery. Such contra rotation increases the frictional stress upon the lane surface during initial contact with the ball. Lofting of the ball increases such effect due to the downward acceleration of the ball just before contact. The lane surface must be relatively hard and unyielding since, if the lane surface allowed the ball to sink significantly into it, such ball would always be trying to climb out of a hole or depressed portion in the surface with a considerable waste of energy as well as possible deviation of the path of the ball due to inequalities in the resiliency of the surface. The bowling ball must also be relatively hard and unyielding to prevent the ball from significantly deforming at its contact point with the lane surface. Any such deformation would result in a corresponding increase in retarding forces upon the ball and interfere with good directionality of the ball.
The traditional bowling lane surface has been formed of relatively narrow boards laid side by side with the narrow dimension vertically oriented. The boards have usually been laid with the edge grain oriented upwardly, often with the boards loosely connected to each other by a tongue-and-groove arrangement, and with nails physically holding the boards together in face-to-face relationship. Normally, a lane may be expected to last for twenty-five years or thereabout, depending upon the usage, so long as the surface is regularly sanded or otherwise equalized to remove damaged wood sections.
The American Bowling Congress, which generally polices the sport, requires that flatness of a lane be maintained within approximately 0.04 inch or less from portion to portion. To reduce damage the surface has normally been made from a hardwood such as maple underlain by a softer material serving as a somewhat cushioned base in the approach and impact lane section as well as the pin deck section and from a cheaper softwood such as pine in the intermediate lane section. Sanding of the surface of the lane to maintain its level and to remove damaged sections which may interfere with the progress of the ball can be continued usually until the vertically arranged boards are sanded down to where they may be partially interlocked with each other by a tongue-and-groove arrangement. If sanding proceeded beyond this point, the boards would lose their interengagement and the lane becomes completely unsatisfactory. Furthermore, where the boards are secured together only by nailing, which was standard in older lanes, sanding cannot proceed beyond a point at which the nails would be exposed. Periodic sanding is obviously expensive and many attempts and suggestions have been made by those in the art to provide a harder, more durable surface which will not wear as rapidly or preferably wear hardly at all. Various synthetic surfaces have been suggested either in the nature of overlays over the normal lane boards, such overlays being either in themselves physical structures or alternatively various synthetic impregnations of the upper surface of the boards. Other suggestions for compositions to fill in dents and inequalities in the surface have been made.
In recent years, most of the suggestions for hardening or otherwise improving the surface of a bowling lane and increasing its wear resistance have involved the use of synthetic materials such as, for example, a melamine external surface, see for example, U.S. Pat. Nos. 4,205,842 and 4,105,843 to G. W. Murray, which disclose the use of a high pressure laminate which simulates a natural wood surface. The use of synthetic surface dressing is also known. In fact, one of the principal surface dressings is ordinary mineral oil which is widely used to increase the playability of the lane surface to facilitate the slip of the ball upon the initial portion of the lane surface and to reduce wear. Such oil dressing came into widespread use just after the Second World War when widespread lofting of the ball by the players began and bowlers began to roll or actually to loft the ball from the middle of the lane rather than from one corner. It is possible to strike the pocket of the pins from one corner, although not at the best angle of approach, with a straight approach. However, the pocket can also be entered from the center of the lane or even the opposite side of the lane if the ball is rolled more or less parallel to the pocket with a side spin on the ball, which side spin causes the ball to curve or "hook" into the pocket.
The lofting of the ball with accompanying spin or "English" on the ball multiplies the stress on the lane surface because of the impact of the lofted ball with the surface, usually at an angle and with the ball spinning at the moment it hits the surface. Such spin not only increases the stress of the striking ball upon the surface of the lane, but also often severely heats the wood and overlying lacquer or other coating leading to splitting and splintering as well as actual micro charring of the wood fibers at the surface of the boards. The application of oil to the lane surface, on the other hand, to increase the lubricity of such surface, considerably reduces the friction of a spinning ball upon striking the surface and also, when a ball is lofted or physically thrown down the lane, decreases the initial impact by allowing the ball to slip upon the surface rather than to, in effect, plough into it. In other words, both the ball and the forces of impact are more easily deflected into parallel relationship with the surface rather than such stresses being directed into the interior of the boards of the lane. The oiling, in addition, has a considerable effect upon the type of game played by the bowler and the skill necessary to play the game.
As indicated, because of the initial triangular arrangement of bowling pins at the end of a bowling lane and the ultimate aim of the game to knock down as many pins as possible with as few bowling balls as possible, it is physically desirable for the bowling ball on the initial roll to enter the so called "pocket" between the leading pin and the following pins while traveling more or less perpendicular with respect to the side of the triangular arrangement of the pins. If the bowling ball strikes the pin arrangement at such perpendicular angle, it has a maximum probability of knocking down all of the pins at once. However, because of the length of the lane, it is physically impossible to roll the ball straight at the pocket at the required angle for most reliably knocking down all of the pins. Consequently, the next best approach may be to roll the ball, usually from the center of the lane, toward a point at which, if the ball has so-called side English or spin, attained by twisting the hand and ball to the side as it is thrown, such ball will, by the time it reaches a point down one side of the lane at which it is more or less opposite the "pocket," have assumed a diagonal movement made up of its original component of motion as it is propelled down the lane plus a transverse component of motion derived from its side English or spin. In effect, the ball assumes a curved overall motion on the surface of the lane not unlike the curve of a baseball thrown in a similar manner, except that the curvature of a baseball is attained by interaction of the spinning ball with the surrounding air, while the curvature of the bowling ball is attained by its interaction with the surface of the bowling lane, the rolling ball having insufficient speed or rotation to have significant interaction with the surrounding air. A further difference is that in the case of a baseball it is desirable to have a maximum curvature of the path of the pitched ball to interfere as much as possible with the aim of the batter at the plate, even though the increased curvature may also make it harder for the pitcher to aim the ball at any given area within the strike zone. With a bowling ball, on the other hand, since the bowling pins do not try to either avoid or strike the ball, it is advantageous for the bowler, so far as accuracy is concerned, to have as little curvature to the path of the ball as possible, while bringing or directing the ball into the pins at the most desirable angle.
A lesser curvature is also less stressful on the physical anatomy of the bowler and tends also to somewhat even the wide difference between the expert player and the average player, an important consideration in keeping the average player interested in the sport. It has consequently, as pointed out above, become the custom in many, if not almost all, bowling centers to provide a very light layer or film of oil upon the surface of the lane extending from the foul line for about twenty to forty feet down the lane. Such light film of oil decreases the initial friction between the ball and the surface of the lane, enabling the surface of the ball to slip more easily upon the surface of the lane and have, in effect, less interaction with the lane. Such slippage or sliding has two principal advantages for the bowler and one principal advantage for the lane.
The principal advantage for the lane is that when the lane is oiled, the lane will not be damaged or worn as much when the ball is laid or even dropped upon the lane, since the friction is not as great. Consequently, the lane is not worn as much by the initial contact of the ball with the lane and the time required for equalization of the speed of rotation of the ball can be greater and such equalization period spread over a longer portion of the lane surface. By the time the ball leaves the oiled section of the lane, it should have gradually reached a surface or rotational speed equivalent to the forward movement of the ball along the lane. In addition, if the ball has been aimed at the "pocket" between the first and the second pins, it will have been given side "English," or a side spin, by twisting the hand of the bowler sharply to one side or the other depending upon which pocket it is intended to enter. Such side spin, if there was no oil film on the lane, would also tend to wear the surface of the lane, but even more importantly, it would, if immediately applied, cause the ball to immediately begin rolling to the side providing a large component of side motion to the path of the ball. The resulting large curvature would mean that the ball would have to be rolled rather sharply toward the side of the lane away from the pocket and allowed to curve back into line with the pocket. While this is possible, it is, as indicated above, rather more difficult to control and to aim than a shallower curve. In addition, if the side spin or rotation of the ball is curtailed in order to flatten the curve and render the aim of the ball less difficult, such ball may, if there is no oil on the lane, not sufficiently spin and may easily be completely stopped or stopped dead so far as side rotation is concerned as soon as it strikes the lane surface so that very little ultimate sidewise motion at all is attained and it is impossible for the ball to enter the "pocket" at the most desirable angle. Consequently, while expert bowlers may be able to negotiate the lane successfully without oil upon the initial portion of the surface, it is much more difficult than when a desirable amount of oil or lubrication is used and even expert bowlers may find it difficult to strike the pocket at all.
When a thin layer of oil is supplied to the initial surface of the bowling lane, i.e. usually to the first 20 to 40 feet of the lane, as the ball strikes the surface of the lane, after having been either slid carefully upon the surface or having been lofted slightly and dropped upon the surface, the ball, when it first strikes the surface, has a component of sidewise rotation and hopefully also a component of forward rotational motion, although many less skillful bowlers may merely throw it down the lane with either no initial forward rotation or even a backward rotation. The initial rotational motion is, however, not as important if the lane is oiled since the ball will slide in the direction it is initially forcefully propelled with very little rotational motion and will, in effect, slide down the lane gradually building up rotational momentum as it starts to roll. Finally, at about the time the ball leaves the oiled portion of the lane, it will already be rotating in the desired forward direction it is supposed to go. In addition, the side spin or English placed upon the ball to the side will be maintained to the side with the ball initially sliding upon the lane to maintain its sidewise rotational momentum.
Since the surface of the oiled lane is, however, not completely frictionless, the sidewise rotational momentum of the ball will gradually cause the ball to start to move to the side until at the end of the oiled section of the lane, it will begin to move definitely to the side, or "hook," rather quickly attaining a sharp curvature to the side which, if it is lined up with the pocket, enables the ball to move directly toward the pocket beginning from a point much nearer the center of the lane than would otherwise be possible.
As will be seen from the above, the application of a small amount of lubricant in the form of a thin layer or film of lubricating oil has certain definite advantages in a commercial bowling establishment, as it renders the game less difficult for the normal bowler, while still maintaining ultimate difficulty for the expert and enabling the expert to demonstrate a superior mastery of the game. Such oiling of the lane also reduces, as explained, wear and tear on the lane.
A layer or thin film of oil, however, also has definite disadvantages. Among these may be listed the:
(a) The disadvantage of having to periodically renew the oil film, PA0 (b) the contamination of the ball with a thin layer of oil picked up from the lane, PA0 (c) contamination of clothing and hands with the oil, PA0 (d) ultimate contamination of the environment with the oil, and PA0 (e) the tendency of the oil to be carried down the lane by the surface of the ball slowly changing conditions of the lane and, in effect, the parameters of the game.
The last disadvantage is one of the most serious, since, as the oil is carried down the lane, the point at which the ball initially begins to roll, or hook sharply to the side will gradually change, lengthening somewhat for each consecutive bowler or contestant whereas it is important and desired to have identical conditions for each player. The oiling of the lane, thus, in effect, prevents the provision of level playing conditions for each contestant. In addition, the periodic renewal of the oil film and its application under strictly controlled conditions is difficult and expensive.
Related to the necessity to apply the oil film under strictly controlled conditions, so that the lubricity of the surface of the lane will be essentially the same from lane to lane and from one bowling center to another, is the propensity of some operators of bowling centers to deliberately place a heavy buildup of lane conditioner, or oil, at a strategic point to aid in directing the ball into the pocket. This increases scores making the local customers happy, but ruining competitive scores between centers. Such "lane blocking" techniques require close supervision by the American Bowling Congress (ABC) to maintain uniformity of bowling conditions throughout the industry.
It has been the dream of many in the industry to do away with the oil film and return to the original uniform conditions of the lane surface. Simply eliminating the oil has not been too attractive, however, since such action would quite likely eliminate many at least occasional bowlers, because of the additional difficulty of the game which such action would lead to. In addition, without the use of the oil, the usual bowling lane does not last too long, since the friction which is always present in bowling would quickly deteriorate the surface by localized overheating and other frictional effects, particularly where the ball first strikes and continuing down the lanes. Some attempts to eliminate the oil have involved merely the provision of stronger, more durable surface materials which can stand up to the frictional wear and tear upon the surface. Others have tried to eliminate the oil by supplying an inherently slippery surface either through composition of the surface or by the use of alternative dressing compounds. This approach has appeared particularly attractive as other types of synthetic surfaces have come into use. However, no really satisfactory oiless surface has hitherto been found.
Examples of attempts to use an inherently slippery surface or alternative slip-inducing dressings are the following:
U.S. Pat. No. 3,670,049 issued Jun. 13, 1972 to A. H. Stein et al. discloses the use of a polyurethane coating composition for finishing bowling lanes. The composition contains from about 0.2 to 10% by weight based upon the polyurethane polymer of a finely divided slip-inducing agent such as polyethylene. This patent thus attempted to combine the hard wear resistant but relatively high frictional characteristics of a polyurethane with the slip characteristics of a polyethylene.
U.S. Pat. No. 4,036,496 issued Jul. 6 19, 1977 to R. Robinson used a polysiloxilane or silicone material as a gloss-imparting agent for the surface of a bowling lane. This is an example of an attempt to provide a longer lasting, non-friction dressing or treatment other than a thin film of mineral oil.
It has been suggested not only to use small particles of polyethylene in the surface of a harder material, but to use a polyethylene or other synthetic polymer having smooth low friction surface characteristics as the lane surface itself. However, problems have been encountered with this simplistic concept and no practical system has been developed. In particular, difficulty has been encountered in keeping the low friction material aligned with itself since it is difficult to maintain a slippery material aligned together. For example, in the use of sheets of synthetic material, it is difficult to keep the edges of adjacent sheets aligned due to a tendency of the edges to be elevated slightly when a heavy bowling ball drops upon or even rolls across the middle of the sheet often depressing the center or middle and slightly elevating the sides or edges. While it is possible to glue down the sheets, adhesive does not, in general, adhere well to a low friction surface and the edges still tend to become elevated. Small inequalities in height between adjacent sheets cause undesirable vibration, small hops, retardation and possible very serious deviation of the path of a bowling ball. Furthermore, synthetic polymers tend to have relatively high coefficients of expansion with temperature changes which have not been easily matched with the coefficient of expansion of the remainder of a bowling lane or otherwise compensated for.
In addition, it is difficult to obtain a surface friction having the general frictional characteristics of an oiled lane surface which has now become the standard in the industry. It has also been difficult to identify a material having both satisfactory surface friction characteristics and strength and durability.
In the present Applicant's previous application, Ser. No. 07/815,387, filed Dec. 31, 1991, the surface of the bowling lane was described as being comprised essentially of individual sheets of relatively slippery synthetic plastic material having the special surface configuration of the invention. While the individual sheets, which are preferably attached to each other and to the lane surface by double-faced tape, have proven effective in practice, certain difficulties have become evident over a period of time. Among these are that with long continued use, the individual sheets sometimes become slightly warped due to the pressure of the ball rolling across them and striking them. Such warpage may be either temporary or relatively permanent and may result in the edge of one plastic sheet extending slightly above an adjacent sheet so that as a ball rolls from one to another it is retarded slightly by rolling or hopping up a slight elevation or rolls from one sheet down onto another. Because of the weight of the ball, the edge of a subsequent sheet is more likely to be slightly higher than lower. These inequalities are difficult to eliminate as a lane ages except by securely adhering the sheets to the underlying lane surface. Permanent adhering, however, in effect, means that a two-faced sheet cannot be turned over to renew a worn surface. Even with the sheets securely adhered to the base, furthermore, the weight of a rolling ball will tend to slightly depress the edge of an initial sheet over which it passes below the surface of a following adjacent synthetic sheet.
It is also advisable to leave expansion cracks or openings between the individual sheets, as explained in the previous application, which cracks can be sealed with a resilient filler, to prevent expansion of the sheets from forcing their edges upwardly at intersections between the sheets. However, with a decrease in temperature, the sheets will pull away from each other providing a crack which the ball has to traverse, possibly causing deviation of the ball. The resilient filler is not always effective to overcome the effects of such crack.
A further difficulty with the system described in Applicant's previous application is that while the use of double-sided adhesive tape to secure the plastic sheets of the invention to underlying structure and to each other is effective in holding the sheets down and also allows them to be readily taken up and reversed as well as to move laterally somewhat to allow for expansion, it has been found that while the sheets can be readily reversed if the lane is heavily used so that such reversal occurs within a few months of the original installation of the lane surface, if the lane is not heavily used and the sheets do not require reversal for a year or more, the adhesive of the tape may deteriorate or alternatively set so that the tape becomes very difficult to remove and leaves an adhesive residue which is not desirable upon the top of the sheet on the active lane surface when reversed.
There has been a need, therefore, for a low-friction, synthetic, long-wear bowling lane surface or lane construction. A need has also become evident for a lane system which does not have detrimental cracks between sheets, that does not warp and that does not require adhesive to secure to the underlying surface or base material.